Geological and Biological Evolution Notes
These notes were taken from the ncdpi website: you should have a copy of this in your notebook
http://scnces.ncdpi.wikispaces.net/file/view/Unpacked_Content_Grade8Science_RevisedSeptember2012.docx.pdf
Students know:
that fossils provide important evidence of how life and environmental conditions have changed. The
earth processes we see today,
including erosion, movement of lithospheric plates, and changes in atmospheric composition, are similar
to those that occurred in the past.
Earth’s history is also influenced by occasional catastrophes, such as the impact of an asteroid or comet.
give clues to the diversity of living things over the history of Earth, give clues to past climate and
surface changes on Earth, and give clues to changes that have occurred with organisms over
time.
the different types of fossils based on how they were formed. The formation process of fossils
varies depending on where and under what environmental conditions they formed.
o Mold fossil – forms when sediments bury an organism and the sediments change into
rock; the organism decays leaving a cavity in the shape of the organism.
o Cast fossil – forms when a mold is filled with sand or mud that hardens into the shape
of the organism.
o Petrified fossil (permineralized fossil) – forms when minerals soak into the buried
remains, replacing the remains, and changing them into rock.
o Preserved fossil – forms when entire organisms or parts of organisms are prevented
from decaying by being trapped in rock, ice, tar, or amber.
Carbonized fossil – forms when organisms or parts, like leaves, stems, flowers, fish, are
pressed between layers of soft mud or clay that hardens squeezing almost all the
decaying organism away leaving the carbon imprint in the rock.
o Trace fossil – forms when the mud or sand hardens to stone where a footprint, trail, or
burrow of an organism was left behind.
history. The geologic time scale began when Earth was formed and goes on until the present. At the end
of each era a mass extinction occurred, many kinds of organisms died out, although there were other
extinctions going on during each period of geologic time. Using the fossil record, paleontologists have
created an idea of the different types of common organisms in each geologic period.
o Precambrian Era
around 4.6 billion years ago.
n and light, (2) the
creation of the Earth, (3) the creation of the atmosphere through volcanic out-gassing,
(4) the creation of the oceans, and (5) the creation of life.
of simple organisms such as jellyfish and sea worms by the end of the
era.
-bodied and had no hard skeleton.
o Paleozoic Era
to
develop early vertebrate fish, then arachnids and insects; later came the first
amphibians, and near the era’s end the reptiles became dominant.
uded simple mosses, ferns, and then cone-bearing plants.
ed plants were common.
amphibians to disappear.
o Mesozoic Era
nant animals of this era, including the various dinosaurs.
also appeared.
increased.
become extinct.
o Cenozoic Era
The diversity of life forms increased.
that various models, diagrams, and pictures can be used to illustrate the vastness of time involved in
geologic time and to show the diversity of life evident across geologic time. Through the illustrations,
not only does the diversity of life-forms increase, but the complexity of those life-forms also increases.
millions of fossils have been collected and studied. The fossil record gives important
information about past life and environments on Earth. Certain fossilized organisms could only
live in specific environments or under particular climate conditions. Extinction of lifeforms as
well as how and when new life-forms appeared is part of the fossil record.
ive age means the age of one object compared to the age of another object.
Relative age does not tell the exact age of an object. The relative age of rocks and fossils can be
determined using two basic methods: ordering of rock layers and index fossils:
o Ordering of Rock Layers Scientists read the rock layers knowing that each layer is deposited on top of
other layers. The law of superposition states that each rock layer is older than the one above it. This law
is used to read rock layers. Using this understanding of layering, scientists infer that the relative age of
the rock or fossil in the rock is older if farther down in the rock layers. Relative dating is best used when
the rock layers have been preserved in their original sequence. Over millions of years, tectonic plate
motion can distort these layers. As a result of this, the youngest layers of rock are not always found on
top, because of folding, breaking, and uplift of layers.
o Index Fossils Certain fossils, called index fossils, can be used to help find the relative age of rock layers.
To be an index fossil –an organism must have lived only during a short part of Earth’s history; many
fossils of the organism must be found in rock layers; the fossil must be found over a wide area of Earth;
the organism must be unique.
The shorter time period a species lived, the better an index it is. A key example of an organism used as
an index fossil are trilobites, a group of hard-shelled animals whose body had three sections, lived in
shallow seas, and became extinct about 245 million years ago. Therefore, if a trilobite is found in a
particular rock layer, it can be compared with trilobites from other layers to estimate the age of the
layer in which it was found.
mate how long ago rocks formed, and to infer the ages of
fossils contained within those rocks. The universe is full of naturally occurring radioactive elements.
Radioactive atoms are inherently unstable; over time, radioactive “parent atoms” decay into stable
“daughter atoms.” When molten rock cools, forming what are called igneous rocks, radioactive atoms
are trapped inside. Afterwards, they decay at a predictable rate. By measuring the quantity of unstable
atoms left in a rock and comparing it to the quantity of stable daughter atoms in the rock, scientists can
estimate the amount of time that has passed since that rock formed.
Absolute geologic dating and relative geologic dating are two methods by which scientists try to
determine the age of geologic evidence.
Carbon-14 dating is an example of absolute dating, and the law of superposition is an example of
relative dating.
Students know:
hat a variety of artifacts are used to determine the geological history of the Earth, as well as how its
life forms have changed over time. Ice cores are cylinders of ice that are drilled out of glaciers and polar
ice sheets. Ice cores play an important role in helping scientists to gain an understanding of the Earth’s
history, particularly how earth’s climate has changed over time. When snow falls it carries with it the
compounds that are in the air at the time. In areas where temperatures are rarely above freezing (ice
sheets and glacial areas), this builds up layer upon layer of compacted snow which becomes ice. Within
these ice layers there is a record of the atmosphere at the time that the snow creating the ice layers fell.
Sedimentary rock makes up about 75% of the rocks on the Earth’s surface. Sedimentary rocks form on
the surface of the Earth, anywhere that sand, mud, or other types of sediment collect. Scientists can
gain an understanding of Earth’s climate, biological, and geologic history by examining the contents of
different layers of sedimentary rock. Sedimentary rock layers can be disturbed by igneous rock. This
happens when molten rock forces it way up through the layers above it. This forms igneous rock
sections within and across the sedimentary layers. The sedimentary rock layers must be there first,
therefore the igneous rock intrusions are younger than the layers it cuts through. Sometime the molten
rock will force its way to the surface and erupt, creating a younger igneous layer at the surface. With
time, more sedimentary layers can form on top of the igneous rock. Igneous rock is always younger than
rock layers it cuts through.
ent
of rock on either side of the fault. Generally, faults occur where there is movement (a slip) of tectonic
plates. Sudden movement of this type is associated with earthquakes. Students know that the two main
types of faults involve dip slips and strike slips. In a dip slip, two pieces of land changetheir vertical
position compared to one another. Afterward, one side of the fault is higher than the other. In a strike
slip, two pieces of land move horizontally.
Students know that:
s the shape of Earth’s surface, has a history of change that is called evolution.
Theory of Evolution, the Plate Tectonics Theory, and the Law of Superposition.
biological evolution accounts for the diversity of species developed through gradual processes over
many generations. Species acquire many of their unique characteristics through biological adaptation,
which involves the selection of naturally occurring variations in populations. Biological adaptations
include changes in structures, behaviors, or physiology that enhance survival and reproductive success
in a particular environment. Similarities among organisms can infer the degree of relatedness:
homologous structures—anatomical and cellular, analogous structures--anatomical and cellular,
embryological similarities—anatomical and cellular, human developmental patterns are similar to those
of other vertebrates.
aces of organisms that lived in the past) can be
compared to one another and to living organisms according to their similarities and differences. Many
thousands of layers of sedimentary rock provide evidence for the long history of the earth and for the
long history of changing life forms whose remains are found in the rocks. Sediments, sand and smaller
particles (sometimes containing the remains of organisms) are gradually buried and cemented together
to form solid rock again. More recently deposited rock layers are more likely to contain fossils
resembling existing species. Thousands of layers of sedimentary rock not only provide evidence of the
history of Earth itself, but also of changes in organisms whose fossil remains have been found in these
layers.
The collection of fossils and their placement in chronological order (e.g., through the location of the
sedimentary layers in which they are found or through radioactive dating) is known as the fossil record.
It documents the existence, diversity, extinction, and change of many life forms throughout the history
of life in Earth. Because of the conditions necessary for their preservation, not all types of organisms
that existed in the past have left fossils that can be retrieved. Anatomical similarities and differences
between various organisms living today and between them and organisms in the fossil record enable the
reconstruction of evolutionary history and the inference of lines of evolutionary descent.
ost species that have lived on the earth are now extinct. Extinction of species is common. Extinction
of species occurs when the environment changes and the individual organisms of that species do not
have the traits necessary to survive and reproduce in the changed environment. Some organisms that
lived long ago are similar to existing organisms, but some are quite different. Extinction of organisms is
apparent in the fossil record.
fy all life on Earth. There are a
number of goals to biological classification, in addition to the obvious need to be able to precisely
describe organisms. Creating a system of classification allows scientists to examine the relationships
between various organisms, and to construct evolutionary trees to explore the origins of life on Earth
and the relationship of modern organisms to historical examples. Biological classification is also referred
to as taxonomy. Comparison of the embryological development of different species also reveals
similarities that show relationships not evident in the fully formed anatomy.
Theory of Evolution: The theory states that species change over time. Living things evolve in response to
changes in their environment.
Charles Darwin is widely known as the “Father of Evolution”. His theory of evolution is the widely held
notion that all life is related and has descended from a common ancestor. As random genetic mutations
occur within an organism's genetic code, the beneficial mutations are preserved because they aid
survival -- a process known as natural selection. These beneficial mutations are passed on to the next
generation.
Over time, beneficial mutations accumulate and the result is an entirely different organism (not just a
variation of the original, but an entirely different creature).
Plate Tectonics Theory: The movements of Earth’s continental and oceanic plates have caused
mountains and deep ocean trenches to form and continually change the shape of Earth’s crust
throughout time. These same movements have caused these plates to pass through different climatic
ones. Natural processes and human activities result in environmental challenges. Sea level changes over
time have expanded and contracted continental shelves, created and destroyed inland seas and shaped
the surface of land. Sea level changes as plate tectonics cause the volume of the oceans and the height
of land to change, as ice caps on land melt or enlarge and/or as sea water expands when ocean water
warms and cools. The processes responsible for changes we observe today are similar to the processes
that have occurred throughout Earth’s history. The evolution of Earth’s living things is strongly linked to
the movements of the lithospheric plates. The movements of the plates cause changes in climate, in
geographic features such as mountains, and in the types of living things in particular places.
Law of Superposition: Many thousands of layers of sedimentary rock provide evidence for the long
history of the earth and for the long history of changing life forms whose remains are found in the rocks
(fossils). More recently deposited rock layers are more likely to contain fossils resembling existing
species.
8.L.4.2
Students know that:
ividuals. Variation exists
in the phenotypes (body structures and characteristics) of the individuals within every population. An
organism’s phenotype may influence its ability to find, obtain, or utilize its resources (food, water,
shelter, etc.) and also might affect the organism’s ability to reproduce.
tions.
Changes in environmental conditions can affect the survival of individual organisms and entire species. If
an environment changes, organisms that have characteristics which are well-suited to the new
environment will be able to survive and reproduce at higher rates than those with less
favorable traits. Therefore, the alleles associated with favorable phenotypes increase in frequency and
become more common and increase the chances of survival of the species.
(those that are “favored” in the environment) are more likely
than others to survive, reproduce and pass these “favorable” traits (such as courting behaviors,
coloration or odors in plants and animals, competitive strength) to their offspring. Those organisms that
do not interact well with the environment are more likely to die or produce fewer offspring than those
organisms having “favored” traits.
within a species there is a variability of phenotypic traits leading to diversity among the organisms of the
species. The greater the diversity, the greater the chances are for that species to survive during
environmental changes.